Short-circuit protection circuit and refrigerant recycling machine power supply circuit

Abstract

The utility model belongs to the technical field of protection circuits, and particularly relates to a short-circuit protection circuit and a refrigerant recycling machine power supply circuit. In order to overcome the defect that when the output of one LDO is short-circuited, the outputs of the other LDOs are also influenced in the existing refrigerant recycling machine powered by multiple LDOs, the utility model adopts the following technical scheme: the short-circuit protection circuit comprises an instantaneous pulse enabling unit, a short-circuit protection unit, a short-circuit protection unit and a short-circuit protection unit, a long-time self-locking unit; a self-locking and short-circuit control unit; a short circuit protection unit; the self-locking and short-circuit control unit is connected to the short-circuit protection unit, and a high-voltage electrode of the long-time self-locking unit is connected to an output electrode of the short-circuit protection unit; when the instantaneous pulse enabling unit is conducted, the self-locking and short-circuit control unit, the short-circuit protection unit and the long-time self-locking unit are all conducted; and when the output electrode of the short-circuit protection unit is short-circuited, the long-time self-locking unit, the short-circuit control unit and the short-circuit protection unit are all cut off. The beneficial effects of the utility model are that the circuit is automatically disconnected when short circuit occurs, and a protection effect is achieved.

Description

Technical Field

[0001] The utility model belongs to the technical field of protection circuits, and in particular relates to a short-circuit protection circuit and a refrigerant recovery machine power supply circuit. Background Art

[0002] In the field of refrigeration technology, for refrigerant recovery machines, according to market feedback, internal short circuits in high and low pressure sensors often occur. When an abnormality occurs in the internal circuit of the high and low pressure sensors and a short circuit occurs, the voltage supplied to the control panel will also be unstable, and the components on the control panel will also become abnormally hot. Overheating of some components will cause abnormal communication between the control panel and the main control board, ultimately leading to the inability to control the motor, and may also cause damage to the control panel and even create a fire hazard.

[0003] After analysis and research, it was found that the cause of the above situation is that the high and low voltage sensors and the main control board (as well as the control panel, buzzer, etc.) use the same power supply. One route is stepped down (usually to 5V) by an LDO (low dropout regulator) to power the high and low voltage sensors, and the other route is stepped down (usually to 3.3V) by another LDO to power the main control board. When the high and low voltage sensors are short-circuited, the output of LDO5V is always short-circuited, burning weak components, and causing the output of LDO3.3V to be unstable, pulling down the input voltage Vin of the control panel, making the normal function of the control panel invalid. The existing refrigerant recovery machine power supply circuit can be referred to Figure 1 .

[0004] Therefore, it is necessary to set a short-circuit protection circuit to prevent the high and low voltage sensors from being affected by the circuits that supply power to them when they are short-circuited, and to avoid affecting the control panel and other components related to the sensor power supply circuit. However, the existing short-circuit protection circuit has its advantages and disadvantages and is not well suited for dual (or more) LDO applications. Summary of the invention

[0005] The utility model aims at the existing refrigerant recovery machine using multiple LDOs for power supply. When the output of one LDO is short-circuited, the outputs of other LDOs are also affected. The utility model provides a short-circuit protection circuit. When the power unit is short-circuited, the power supply to the power unit is quickly cut off. When used for multiple LDOs, when the output of a certain LDO is short-circuited, the output of the LDO can be automatically cut off, thereby protecting the outputs of other LDOs. The utility model also provides a power supply circuit for a refrigerant recovery machine using the short-circuit protection circuit.

[0006] To achieve the above purpose, the utility model adopts the following technical solution: a short circuit protection circuit, the short circuit protection circuit comprises:

[0007] Instantaneous pulse enabling unit, unidirectional conduction;

[0008] Long-term self-locking unit, one-way conduction;

[0009] Self-locking and short-circuit control unit;

[0010] A short-circuit protection unit, the input pole of which is connected to the positive pole of the power supply, and the output pole of which is connected to the power consumption unit;

[0011] The low voltage poles of the instantaneous pulse enabling unit and the long-time self-locking unit are respectively connected to the self-locking and short-circuit control unit, the self-locking and short-circuit control unit is connected to the short-circuit protection unit, and the high voltage pole of the long-time self-locking unit is connected to the output pole of the short-circuit protection unit;

[0012] When the instantaneous pulse enabling unit is turned on, the self-locking and short-circuit control unit, the short-circuit protection unit and the long-time self-locking unit are all turned on;

[0013] When the power consumption unit connected to the output pole of the short-circuit protection unit is short-circuited, the long-time self-locking unit, the short-circuit control unit and the short-circuit protection unit are all cut off.

[0014] As an improvement, the instantaneous pulse enabling unit includes a diode D1; the conduction time of the instantaneous pulse enabling unit is in the millisecond level.

[0015] As an improvement, the long-time self-locking unit includes a diode D2.

[0016] As an improvement, the self-locking and short-circuit control unit includes an NPN transistor Q2.

[0017] As an improvement, the self-locking and short-circuit control unit includes an NPN transistor Q2 or an NMOS transistor Q4; and the short-circuit protection unit includes a PMOS transistor Q1 or a PNP transistor Q3.

[0018] As an improvement, the self-locking and short-circuit control unit includes an NPN transistor Q2, the short-circuit protection unit includes a PMOS tube Q1, a resistor R4 is provided between the low-voltage poles of the diodes D1 and D2 and the base of the NPN transistor Q2, the emitter of the NPN transistor Q2 is grounded, the resistor R4 is grounded through a resistor R5, the other pole of the resistor R5 is connected to the base of the NPN transistor Q2, and a resistor R3 is provided between the collector of the NPN transistor Q2 and the G stage of the PMOS tube Q1.

[0019] As an improvement, the S and G stages of the PMOS tube Q1 are connected to the positive pole of the power supply, the D stage is connected to the power-consuming unit, and a resistor R2 is provided between the G stage and the positive pole of the power supply.

[0020] As an improvement, the self-locking and short-circuit control unit includes an NMOS tube Q4; the short-circuit protection unit includes a PNP transistor Q3, a resistor R4 is provided between the low-voltage poles of the diodes D1 and D2 and the G stage of the NMOS tube Q4, the S pole of the NMOS tube Q4 is grounded, the resistor R4 is grounded through a resistor R5, the other pole of the resistor R5 is connected to the G stage of the NMOS tube Q4, and a resistor R3 is provided between the D pole of the NMOS tube Q4 and the base of the PNP transistor Q3.

[0021] As an improvement, the base and emitter of the PNP transistor Q3 are connected to the positive electrode of the power supply, the collector of the PNP transistor Q3 is connected to the power-consuming unit, and a resistor R2 is provided between the base and emitter of the PNP transistor Q3.

[0022] The power supply circuit of the refrigerant recovery machine includes the aforementioned short-circuit protection circuit.

[0023] As an improvement of the power supply circuit of the refrigerant recovery machine, the power supply circuit of the refrigerant recovery machine also includes:

[0024] A first LDO, an input end of which is connected to the positive electrode of the power supply, and an output end of which is connected to the input electrode of the short-circuit protection unit;

[0025] The second LDO has its input end connected to the positive pole of the power supply and its output end connected to the main control board;

[0026] The instantaneous high level generating unit provides an instantaneous high level to the instantaneous pulse enabling unit, so that the instantaneous pulse enabling unit is turned on.

[0027] As an improvement to the refrigerant recovery machine power supply circuit, the output pole of the short-circuit protection unit is connected to the high-voltage sensor and the low-voltage sensor, one end of the high-voltage sensor and the low-voltage sensor is grounded, and the refrigerant recovery machine power supply circuit also includes a capacitor C5 connected in parallel with the high-voltage sensor and the low-voltage sensor.

[0028] The beneficial effects of the short-circuit protection circuit of the utility model are: it includes a unidirectionally conductive instantaneous pulse enabling unit, a unidirectionally conductive long-time self-locking unit, a self-locking and short-circuit control unit, and a short-circuit protection unit; when the instantaneous pulse enabling unit is turned on, the self-locking and short-circuit control unit, the short-circuit protection unit, and the long-time self-locking unit are all turned on; when the power-consuming unit connected to the output pole of the short-circuit protection unit is short-circuited, the long-time self-locking unit, the short-circuit control unit, and the short-circuit protection unit are all cut off, so that when the power-consuming unit at the output pole of the short-circuit protection unit is short-circuited, the short-circuit protection unit is disconnected to prevent damage.

[0029] The power supply circuit of the refrigerant recovery machine of the utility model adopts the short-circuit protection circuit of the utility model and has all the beneficial effects of the short-circuit protection circuit of the utility model. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 The invention is a circuit schematic diagram of an existing refrigerant recovery machine power supply circuit.

[0031] Figure 2 It is a circuit schematic diagram of a power supply circuit of a refrigerant recovery machine in Embodiment 1 of the present utility model.

[0032] Figure 3 It is a circuit schematic diagram of a power supply circuit of a refrigerant recovery machine in Embodiment 2 of the present utility model. DETAILED DESCRIPTION

[0033] The technical solutions of the embodiments of the present invention are explained and described below, but the following embodiments are only preferred embodiments of the present invention, not all. Based on the embodiments in the implementation mode, other embodiments obtained by those skilled in the art without creative work are all within the protection scope of the present invention.

[0034] See also Figure 2 and Figure 3 , the short-circuit protection circuit of the embodiment of the utility model, the short-circuit protection circuit comprises:

[0035] Instantaneous pulse enabling unit, unidirectional conduction;

[0036] Long-term self-locking unit, one-way conduction;

[0037] Self-locking and short-circuit control unit;

[0038] A short-circuit protection unit, the input pole of which is connected to the positive pole of the power supply, and the output pole of which is connected to the power consumption unit;

[0039] The low voltage poles of the instantaneous pulse enabling unit and the long-time self-locking unit are respectively connected to the self-locking and short-circuit control unit, the self-locking and short-circuit control unit is connected to the short-circuit protection unit, and the high voltage pole of the long-time self-locking unit is connected to the output pole of the short-circuit protection unit;

[0040] When the instantaneous pulse enabling unit is turned on, the self-locking and short-circuit control unit, the short-circuit protection unit and the long-time self-locking unit are all turned on;

[0041] When the power consumption unit connected to the output pole of the short-circuit protection unit is short-circuited, the long-time self-locking unit, the short-circuit control unit and the short-circuit protection unit are all cut off.

[0042] The beneficial effects of the short-circuit protection circuit of the utility model are: it includes a unidirectionally conductive instantaneous pulse enabling unit, a unidirectionally conductive long-time self-locking unit, a self-locking and short-circuit control unit, and a short-circuit protection unit; when the instantaneous pulse enabling unit is turned on, the self-locking and short-circuit control unit, the short-circuit protection unit, and the long-time self-locking unit are all turned on; when the power-consuming unit connected to the output pole of the short-circuit protection unit is short-circuited, the long-time self-locking unit, the short-circuit control unit, and the short-circuit protection unit are all cut off, so that when the power-consuming unit at the output pole of the short-circuit protection unit is short-circuited, the short-circuit protection unit is disconnected to prevent damage.

[0043] Embodiment 1

[0044] See also Figure 2 The power supply circuit of the refrigerant recovery machine of the first embodiment of the utility model includes a short-circuit protection circuit, and the short-circuit protection circuit includes:

[0045] Instantaneous pulse enabling unit, unidirectional conduction;

[0046] Long-term self-locking unit, one-way conduction;

[0047] Self-locking and short-circuit control unit;

[0048] A short-circuit protection unit, the input pole of which is connected to the positive pole of the power supply, and the output pole of which is connected to the power consumption unit;

[0049] The low voltage poles of the instantaneous pulse enabling unit and the long-time self-locking unit are respectively connected to the self-locking and short-circuit control unit, the self-locking and short-circuit control unit is connected to the short-circuit protection unit, and the high voltage pole of the long-time self-locking unit is connected to the output pole of the short-circuit protection unit;

[0050] When the instantaneous pulse enabling unit is turned on, the self-locking and short-circuit control unit, the short-circuit protection unit and the long-time self-locking unit are all turned on;

[0051] When the power consumption unit connected to the output pole of the short-circuit protection unit is short-circuited, the long-time self-locking unit, the short-circuit control unit and the short-circuit protection unit are all cut off.

[0052] In this embodiment, the instantaneous pulse enabling unit includes a diode D1.

[0053] In this embodiment, the long-time self-locking unit includes a diode D2.

[0054] In this embodiment, the self-locking and short-circuit control unit includes an NPN transistor Q2.

[0055] In this embodiment, the short circuit protection unit includes a PMOS tube Q1.

[0056] In this embodiment, a resistor R4 is provided between the low voltage electrodes of the diodes D1 and D2 and the base of the NPN transistor Q2, the emitter of the NPN transistor Q2 is grounded, the resistor R4 is grounded through a resistor R5, the other electrode of the resistor R5 is connected to the base of the NPN transistor Q2, and a resistor R3 is provided between the collector of the NPN transistor Q2 and the G electrode of the PMOS tube Q1.

[0057] In this embodiment, the S stage (source) and G stage (gate) of the PMOS tube Q1 are connected to the positive power supply, the D stage (drain) is connected to the power unit, and a resistor R2 is provided between the G stage and the positive power supply.

[0058] In this embodiment, the refrigerant recovery machine power supply circuit also includes:

[0059] A first LDO, an input end of which is connected to the positive electrode of the power supply, and an output end of which is connected to the input electrode of the short-circuit protection unit;

[0060] The second LDO has its input end connected to the positive pole of the power supply and its output end connected to the main control board;

[0061] The instantaneous high level generating unit provides an instantaneous high level to the instantaneous pulse enabling unit, so that the instantaneous pulse enabling unit is turned on.

[0062] In this embodiment, the first LDO inputs 12V and outputs 5V. The second LDO inputs 12V and outputs 3.3V. The first LDO and the second LDO are connected in parallel. The related structures of the first LDO and the second LDO can refer to the drawings and the prior art.

[0063] In this embodiment, the instantaneous high level is generated by the main control board. The duration of the instantaneous high level is 100ms (the duration is set accordingly according to actual needs).

[0064] In this embodiment, the output electrode of the short circuit protection unit is connected to the high voltage sensor and the low voltage sensor, one end of the high voltage sensor and the low voltage sensor is grounded. The high voltage sensor and the low voltage sensor are connected in parallel and are also connected in parallel with the capacitor C5.

[0065] In this embodiment, when the high-pressure or low-pressure sensor is short-circuited, a prompt circuit or the like may be provided to remind the user.

[0066] The principle of short-circuit protection of the power supply circuit of the refrigerant recovery machine of the first embodiment of the utility model is: before supplying power to the high-voltage sensor and the low-voltage sensor, the diode D1 is turned off, the diode D2 is turned off, the NPN transistor Q2 is turned off, and the PMOS tube Q1 is turned off; when the high-voltage sensor and the low-voltage sensor need to work, power is supplied to the high-voltage sensor and the low-voltage sensor, and the power supply process is: first operate the main control board, the main control board generates an instantaneous high level of 100ms, so that the diode D1 is turned on, after the diode D1 is turned on, the NPN transistor Q2 is turned on, after the NPN transistor Q2 is turned on, the PMOS tube Q1 is turned on, at this time the power from the first LDO After the voltage passes through the PMOS tube Q1, the diode D2 is turned on (only about 20ms is needed). The diode D2 makes the NPN transistor Q2 and the PMOS tube Q1 always in the on state, so that the first LDO stably supplies power to the high-voltage sensor and the low-voltage sensor. After 100ms, D1 is turned off without affecting the conduction of the NPN transistor Q2 and the PMOS tube Q1. When the high-voltage sensor and / or the low-voltage sensor is short-circuited internally, the voltage drop of the positive electrode of the diode D2 is zero, the diode D2 is turned off, the NPN transistor Q2 is disconnected, and the PMOS tube Q1 is also disconnected, thereby recovering to the state before power is supplied to the high-voltage sensor and the low-voltage sensor.

[0067] The beneficial effect of the refrigerant recovery machine power supply circuit of the first embodiment of the utility model is that its short-circuit protection circuit includes a unidirectional instantaneous pulse enabling unit, a unidirectional long-time self-locking unit, a self-locking and short-circuit control unit, and a short-circuit protection unit. When the instantaneous pulse enabling unit is turned on, the self-locking and short-circuit control unit, the short-circuit protection unit and the long-time self-locking unit are all turned on (the instantaneous pulse enabling unit, the self-locking and short-circuit control unit, the short-circuit protection unit and the long-time self-locking unit are turned on in sequence). When the power-consuming unit connected to the output pole of the short-circuit protection unit is short-circuited, the long-time self-locking unit, the short-circuit control unit and the short-circuit protection unit are all cut off (or disconnected), so that when the power-consuming unit (high-voltage sensor, low-voltage sensor) at the output pole of the short-circuit protection unit is short-circuited, the short-circuit protection unit is disconnected to prevent damage; the response speed is fast.

[0068] Embodiment 2

[0069] See also Figure 3 The power supply circuit of the refrigerant recovery machine of the second embodiment is different from the first embodiment in that the NPN transistor Q2 is replaced by the NMOS transistor Q4, and the PMOS transistor Q1 is replaced by the PNP transistor Q3.

[0070] In this embodiment, the power supply circuit of the refrigerant recovery machine includes a short-circuit protection circuit, and the short-circuit protection circuit includes:

[0071] Instantaneous pulse enabling unit, unidirectional conduction;

[0072] Long-term self-locking unit, one-way conduction;

[0073] Self-locking and short-circuit control unit;

[0074] A short-circuit protection unit, the input pole of which is connected to the positive pole of the power supply, and the output pole of which is connected to the power consumption unit;

[0075] The low voltage poles of the instantaneous pulse enabling unit and the long-time self-locking unit are respectively connected to the self-locking and short-circuit control unit, the self-locking and short-circuit control unit is connected to the short-circuit protection unit, and the high voltage pole of the long-time self-locking unit is connected to the output pole of the short-circuit protection unit;

[0076] When the instantaneous pulse enabling unit is turned on, the self-locking and short-circuit control unit, the short-circuit protection unit and the long-time self-locking unit are all turned on;

[0077] When the power consumption unit connected to the output pole of the short-circuit protection unit is short-circuited, the long-time self-locking unit, the short-circuit control unit and the short-circuit protection unit are all cut off.

[0078] In this embodiment, the instantaneous pulse enabling unit includes a diode D1.

[0079] In this embodiment, the long-time self-locking unit includes a diode D2.

[0080] In this embodiment, the self-locking and short-circuit control unit includes an NMOS transistor Q4; and the short-circuit protection unit includes a PNP transistor Q3.

[0081] In this embodiment, a resistor R4 is provided between the low voltage poles of the diodes D1 and D2 and the G pole of the NMOS tube Q4, the S pole of the NMOS tube Q4 is grounded, the resistor R4 is grounded through a resistor R5, the other pole of the resistor R5 is connected to the G pole of the NMOS tube Q4, and a resistor R3 is provided between the D pole of the NMOS tube Q4 and the base of the PNP transistor Q3.

[0082] In this embodiment, the base and emitter of the PNP transistor Q3 are connected to the positive electrode of the power supply, the collector of the PNP transistor Q3 is connected to the power-consuming unit, and a resistor R2 is provided between the base and emitter of the PNP transistor Q3.

[0083] The principle of short-circuit protection of the power supply circuit of the refrigerant recovery machine of the second embodiment of the utility model is: before supplying power to the high-voltage sensor and the low-voltage sensor, the diode D1 is turned off, the diode D2 is turned off, the NMOS tube Q4 is turned off, and the PNP transistor Q3 is turned off; when the high-voltage sensor and the low-voltage sensor are required to work, power is supplied to the high-voltage sensor and the low-voltage sensor, and the power supply process is: first operate the main control board, the main control board generates an instantaneous high level of 100ms, so that the diode D1 is turned on, after the diode D1 is turned on, the NMOS tube Q4 is turned on, after the NMOS tube Q4 is turned on, the PNP transistor Q3 is turned on, and at this time the voltage from the first LDO After passing through the PNP transistor Q3, the diode D2 is turned on (only about 20ms is needed). The diode D2 makes the NMOS transistor Q4 and the PNP transistor Q3 always in the on state, so that the first LDO stably supplies power to the high-voltage sensor and the low-voltage sensor. After 100ms, D1 is turned off without affecting the conduction of the NMOS transistor Q4 and the PNP transistor Q3. When the high-voltage sensor and / or the low-voltage sensor is short-circuited internally, the voltage drop of the positive electrode of the diode D2 is zero, the diode D2 is turned off, the NMOS transistor Q4 is disconnected, and the PNP transistor Q3 is also disconnected, thereby restoring to the state before power is supplied to the high-voltage sensor and the low-voltage sensor.

[0084] In other embodiments, the self-locking and short-circuit control unit may include an NPN transistor Q2, and the short-circuit protection unit may include a PNP transistor Q3; or, the self-locking and short-circuit control unit may include an NMOS transistor Q4, and the short-circuit protection unit may include a PMOS transistor Q1.

[0085] The above is only a specific implementation of the invention, but the protection scope of the invention is not limited thereto. Those skilled in the art should understand that the invention includes but is not limited to the contents described in the above specific implementation. Any modification that does not deviate from the functional and structural principles of the invention will be included in the scope of the claims.

Claims

1. A short circuit protection circuit, characterized in that: The short circuit protection circuit comprises: Instantaneous pulse enabling unit, unidirectional conduction; Long-term self-locking unit, one-way conduction; Self-locking and short-circuit control unit; A short-circuit protection unit, the input pole of which is connected to the positive pole of the power supply, and the output pole of which is connected to the power consumption unit; The low voltage poles of the instantaneous pulse enabling unit and the long-time self-locking unit are respectively connected to the self-locking and short-circuit control unit, the self-locking and short-circuit control unit is connected to the short-circuit protection unit, and the high voltage pole of the long-time self-locking unit is connected to the output pole of the short-circuit protection unit; When the instantaneous pulse enabling unit is turned on, the self-locking and short-circuit control unit, the short-circuit protection unit and the long-time self-locking unit are all turned on; When the power consumption unit connected to the output pole of the short-circuit protection unit is short-circuited, the long-time self-locking unit, the short-circuit control unit and the short-circuit protection unit are all cut off.

2. The short circuit protection circuit according to claim 1, characterized in that: The instantaneous pulse enabling unit includes a diode D1; the conduction time of the instantaneous pulse enabling unit is in the millisecond level; and the long-time self-locking unit includes a diode D2.

3. The short circuit protection circuit according to claim 2, characterized in that: The self-locking and short-circuit control unit includes an NPN transistor Q2 or an NMOS transistor Q4; the short-circuit protection unit includes a PMOS transistor Q1 or a PNP transistor Q3.

4. The short circuit protection circuit according to claim 3, characterized in that: The self-locking and short-circuit control unit includes an NPN transistor Q2, the short-circuit protection unit includes a PMOS tube Q1, a resistor R4 is provided between the low-voltage poles of the diodes D1 and D2 and the base of the NPN transistor Q2, the emitter of the NPN transistor Q2 is grounded, the resistor R4 is grounded through a resistor R5, the other pole of the resistor R5 is connected to the base of the NPN transistor Q2, and a resistor R3 is provided between the collector of the NPN transistor Q2 and the G stage of the PMOS tube Q1.

5. The short circuit protection circuit according to claim 4, characterized in that: The S and G stages of the PMOS tube Q1 are connected to the positive electrode of the power supply, the D stage is connected to the power-consuming unit, and a resistor R2 is arranged between the G stage and the positive electrode of the power supply.

6. The short circuit protection circuit according to claim 3, characterized in that: The self-locking and short-circuit control unit includes an NMOS tube Q4; the short-circuit protection unit includes a PNP transistor Q3, a resistor R4 is provided between the low-voltage poles of the diodes D1 and D2 and the G stage of the NMOS tube Q4, the S pole of the NMOS tube Q4 is grounded, the resistor R4 is grounded through a resistor R5, the other pole of the resistor R5 is connected to the G stage of the NMOS tube Q4, and a resistor R3 is provided between the D pole of the NMOS tube Q4 and the base of the PNP transistor Q3.

7. The short circuit protection circuit according to claim 6, characterized in that: The base and emitter of the PNP transistor Q3 are connected to the positive electrode of the power supply, the collector of the PNP transistor Q3 is connected to the power-consuming unit, and a resistor R2 is arranged between the base and emitter of the PNP transistor Q3.

8. The power supply circuit of the refrigerant recovery machine is characterized by: The refrigerant recovery machine power supply circuit includes the short-circuit protection circuit described in any one of claims 1 to 7.

9. The power supply circuit of the refrigerant recovery machine according to claim 8, characterized in that: The refrigerant recovery machine power supply circuit also includes: A first LDO, an input end of which is connected to the positive electrode of the power supply, and an output end of which is connected to the input electrode of the short-circuit protection unit; The second LDO has its input end connected to the positive pole of the power supply and its output end connected to the main control board; The instantaneous high level generating unit provides an instantaneous high level to the instantaneous pulse enabling unit, so that the instantaneous pulse enabling unit is turned on.

10. The power supply circuit of the refrigerant recovery machine according to claim 9, characterized in that: The output pole of the short circuit protection unit is connected to the high pressure sensor and the low pressure sensor, one end of the high pressure sensor and the low pressure sensor is grounded, and the refrigerant recovery machine power supply circuit also includes a capacitor C5 connected in parallel with the high pressure sensor and the low pressure sensor.

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